Fuel injection apparatus



Oct. 24, .1939. E. SCHAEREN 2,177,120

FUEL INJECTION APPARATUS Filed Aug. 31, 1937, 2 Sheets-Sheet 1 Invenior Oct. 24, 1939. E. SCHAEREN FUEL INJECTION APPARATUS Filed Aug. 31, 1937 2 Sheets-Sheet 2 3m entor Fawn/ 4: SW 33 90 4 Gttornegs Patented a. 24, 1939 PATENT OFFICE I FUEL INJECTION APPARATUS Ernst Schaeren, Soleure, Switzerland, assignor to Scintilla, Ltd., Soleure, Switzerland, a corporation of Switzerland Application August 31, 1937, Serial No. 161,858

' In Switzerland September 9, 1936 10 Claims.

My invention relates to fuel injection apparatus especially for internal combustion engines and more particularly'to such apparatus comprising in combination an injection pump, a feeding pump adapted for supplying fuel to the latter, and governing means influenced by the pressure of fuel supplied by the said feeding pump.

One of the objects of my invention is to provide a neat and compact arrangement of the said elements of the apparatus, so that the lat-- ner in which my invention is carried out, and it will be lmderstood that. while I have described.

what may be considered as a preferable embodias meat of my invention, I do not limit myself to the precise conditions or proportions set forth, or to the particular type of the said elements herein described, as they may be elected and varied by those skilled in the art in accordance with the a0 particular purposes for which they are intended,

and the conditions under which they are to be utilized.

In the accompanying drawings, Fig. 1 shows, partly in longitudinal section on 35 the line B- B of Fig. 2, a fuel injection apparatus comprising an injection pump, a feeding pump, and regulating means.

' 2 is a horizontal section on the line AA of 110 Fig. 3 is a vertical cross section on the lines D-D of Figsul and 2 and shows part of the regulating means at a larger scale. 7 Fig. 4 is a vertical cross section on the lines 0+0 of Figs. 1 and 2 to show the working part 45 of the injection pump.

The injection pump I may be of any suitable construction and is represented as a 4-cylinder piston pump of usual design. In each cylinder 39 a piston 29 is moved upwards by a cam 6| 50 on thecam shaft 25 and downwards by the spring 3|, a guided pusher 68 provided with a roller 69 being interposed between the cam 6| and the foot .of piston 29. The working chamber 62 within the cylinder 30 communicates with the fuel supply 35 chamber 33 through a port 32 controlled by the her object of my invention is to providetop edge 63 of the piston 29, and with a by-pass chamber 35 through another port 34 controlled by the spiral cut-oft edge 64 of the said piston. An injection conduit 36 leads from the working chamber 62 through a non-return valve 65 to an 5. injection device not represented in the drawings. The piston 29 has a cross" guide 66 engaging longitudinal slots 61 of the gear wheel 31 so as to be angularly coupled with the latter though free to be reciprocated in an axial direction. A longitudinally displaceable rack 38 meshes the gear wheels 3'! of all cylinders of the pump. During the upward or displacing stroke of the piston 29, the inlet port 32 is closed by the top edge 63 of the piston; then fuel is delivered from the working chamber 62, through the non-return valve 65 and the injection conduit 36. When the cut-off edge 64 uncovers the by-pass port 34, pressure is released in the working chamber 62 and the fuel delivery through the conduit 36 ceases. The edge 64 being spiral, the time at which the by-pass port 34 is uncovered, and consequently the useful delivery stroke of the piston 29 and the quantity of fuel displacedfrom the working chamber 62 into the conduit 36 vary according tothe angular position of the said piston. The said angular position may be modified by longitudinally displacing the described rack 38, and it will be assumed that a displacement thereof to the left (as shown in Figs. 1 and'2 of the drawings) causes a diminution of the fuel quantity delivered to the conduits 36 for being injected.

The precise formation and porting of the cylinder 30 and piston 29 are not claimed herein and are illustrated merely as one acceptable known A combustion engine in a way not represented. A

gear wheel 5 is keyed to the shaft 4 and meshes with a second gearwheel 6 rotatably supported in the casing 8 and the cover piece I9. Both said gearwheels form a gearwheel pump adapted to displace fuel arriving through a conduit 59 from a tank not shown in the drawings, into the duct 1 provided in the casing 8. The duct 7 is connected to the fuel supply chamber 33 of the pump by means of the passage 55 and leads to a cylinder in which a piston l0 loaded by a spring 9 by the edge of its face controls the cross-section of outlet ports so as to keep the fuel pressure in the duct 1 substantially constant. The outlet ports issue into an annular chamber l2 which is connected by a passage 51 to the by-pass chamber 35 of the injection pump I and by a passage I3 to the adjustable throttling opening [4. From the latter a return conduit |5 joins the collecting line 60 which leads back to the fuel tank in a way not shown in the drawing. Through the duct l1 and the annular groove 8 in the cover piece l9 and through the ports 20 in the hub of theidisplacement gearwheel 5, the passage |3 also communicates'with the cylinder l6 formed in the said hub. The cylinder I6 is fitted by an adjusting piston 2|, the dogs 22 of which engage grooves 23 provided in the hub wall and running parallel to the axis of the latter. A spring 24 abutting the adjusting piston 2| counteracts the fuel pressure in the space I6. The drive end of the cam- .shaft 25 of the injection pump carries a bushing 26 provided with a high pitch male thread which engages a corresponding female thread in the bore 21 of the piston 2|.

. The governor 3 comprises a control cylinder 40 containing a. piston 4| acted upon by a spring 43 which separates two spaces 45 and 41 in the said servomotor cylinder. The space 41 communicates with the fuel supply chamber- 33 of the injection pump I through a conduit 54.and .with the space 45 through a restricted passage 49 in the piston 43. The latter carries an extension provided with a longitudinal bore 46 which is connected by lateral ports to the chamber 45 and issues in the space 44. j

Through the space surrounding the spring 42 and suitable connecting passages, the space 44 communicates with the collecting sump formed in the bottomof the governor casing and connected to the collecting line 60 which leads back to the fuel tank. The issue of the passage 46 in the space 44 cooperates with the face of an extension 48 of the control piston 4| so as to form a restricted opening the cross-section of which depends on the relative position of the pistons 4| and 43. The rod 50 of the piston 43 engages the arm 5| of a bell-crank lever rotatably supported on the shaft 52; the other arm 53 "of this lever is linked ta the rack 36.

The fuel quantity displaced in a given time into the passage 1 by the wheels 5, 60f the feeding pump increases with the speed of the internal combustion engine. One part of this fuelquantity flows into the fuel supply chamber 33 of-the injection pump and thence isdrawn into the cylinders 36; the remainder leaves through the outlet-ports II which are uncovered by the edge of the piston It so far as it is necessary in order that the fuel pressure in the duct 1 which also acts upon the piston' It may counterbalance the force of the'spring 9. The fuel pressure in the duct 1, which also prevails in the suction chamber 33 of the injection pump-and in-the chamber 41 of the servomotor cylinder in the governor, therefore remains approximately constant. The fuel quantity leaving in the unity of time through the outlet ports II and the throttling opening l4, and therefore the fuel pressure in the passage l3,

in the cylinder l6 of the injection timing device,- 5

in the by-pass chamber 35 of the injection pump and in the control cylinder 46 of the governor 3 increase with the speed of the internal combustion engine. As it increases, the pressure in the cylinder 5 displaces the adjusting piston 2| of 1 the injection timing device against the force of the spring 24, so that by means of the high pitch thread the bushing 26 together with the camshaft 25 carrying it are rotated with reference to the gearwheel 5 and the driving shaft 4, to which the 15 latter is keyed, and the injection is caused to take place earlier in the working cycle of the internal combustion engine.

In the governor 3 a part of the fuel delivered by the feeding pump flows back to the'fuel tank 20 from the space 41 through'the restricted passage 49, the space 45, the passage 46 and the space 44. If the speed of the internal combustion en- 'gine rises so high-that the fuel pressure in the control cylinder 46 is able to overcome the force 25 between the said face and'that of the extension 30 48 then increases and causes the fuel pressure in the space 45 to rise, so that the piston 43 is displaced by the excess pressure, draws the rack 38 to the left and diminishes the fuel quantity delivered by the fuel pump into the injection con 3 duits 36. Thus, the intem al combustionengine can no more increase its speed of rotation.

What I claim is: 1; Fuel injection apparatus comprising in combiriation an injection pump body having a fuel 6 supply chamber and a second fuel chamber formed thereirT, injection pump means in said injection pump body adapted for drawing fuel out of said fuel supply chamber, a feedingpump body having a delivery chamber, an-auxiliary chamber, 45 ports connecting said delivery chamber to said auxiliary chamber, and a restricted outlet passage issuing from said auxiliary chamber formed therein, said feeding pump body being affixed to one side of said injection pump body, said delivwe cry chamber in said feeding pump body communicating with said fuel supply chamber in said injection pump body and said auxiliary chamber in said feeding pump body communicating with said second fuel chamber in said injection pump 55 body, feeding pump means in said feeding pump body adapted to pump fuel into said delivery chamber, a pressure regulating deviceadapted to control said ports in accordance with the pressure in said delivery chamber, a governor body 60 slidably fitting said control cylind r so as to bound 65 therein a control chamber, sai governor body being aflixed to the opposite side of said injec-' I tion pump body, said servomotor chamber communicating with said fuel supply chamber and said control chamber communicating with said second fuel chamber in said injectionpump body.

2. Fuel injection apparatus comprising incombination an injection pump body having a'fuel chamber formed therein, a feeding pump body having a pressure space and a restricted outlet issuing from said pressure space formed therein, said feeding pump body being affixed to one side of said injection pump body, said pressure space in said feeding pump body communicating with .said fuel chamber in. said injection pump body, pumping means provided in said feeding pump body and adapted to pump fuel into said pressure space, a governor body having a pressure chamber formed therein, said governor body being affixed to the opposite side of said injection pump body, said pressure chamber in said governor body communicating with said fuel chamber in said injection pump body. 3. The combination of a fuel pump for delivering measured charges of liquid fuel to an engine; a member shift-able to vary the quantity delivered per charge; a fluid pressure operated servomotor for shifting said member; a fluid pressure responsive controller for said servomotor; a drive shaft adapted to be driven intimed relation by the as motive pressure fluid to said servomotor.

4. The combination defined in claim 3 in which a substantially unitary body is afforded by three closely connected housings, one of which houses the fuel pump, another houses the servomotor with its controller, and the third houses the booster pump; and all pressure fluid flow passages between the recited elements areformed as ports internal to said unitary body.

5. The combination with the structure of claim 3 of yielding loading means for the servomotor controller; and operator-operated means for variably stressing said loading means.

6. The combination of a fuel pump for delivering measured charges of fuel to an engine; a member shiftable to vary the quantity delivered per charge; a fluid pressure operated servomotor for shifting said member; a fluid pressure operated controller for said servomotor; a driving shaft arranged to be driven by the engine in timed relation thereto; fluid pressure operated timing means forming an adjustable operating connection between said driving shaft and said pump; a booster pump driven by said driving to said fuel pump, and to said servornotor; a loaded vent valve for holding a substantially uniform back pressure on fuel delivered by said. booster pump regardless of changes of speed thereof; flow restricting means beyond said vent valve for retaining a back pressure which increases with speed of said booster pump; and means for subjecting said servomotor controller and said timing means to the last named back pressure.

'7. The combination defined in claim 6 in which the recited instrumentalities are housed in a substantially unitary housing, and all pressure chambers and flow connections for fluid under pressure between said instrumentalities are wholly within said housing.

8, The combination defined in claim 6 in which a substantially unitary body is afforded ,by three closely connected housings, one of which houses the fuel pump, another the servomotor with its controller, and the third the booster pump, and the timing means; and all pressure fluid flow passages between the above recited elements are formed as ports in said unitary body.

9. The combination of a fuel pump for delivering measured charges of liquid fuel to an engine; a member shiftable to vary the quantity delivered per charge; a fluid pressure operated servomotor for shifting said member; a fluid pressure responsive controller for said servomotor; a drive shaft adapted to be driven in timed relation by the engine; a fluid pressure responsive timer forming an adjustable driving connection between said shaft and pump; a booster pump driven by said drive shaft; connections for supplying liquid fuel to said booster pump; two flow restricting means in series arranged to develop two back pressures on liquid fuel discharged by said pump and so arranged that one back pressure is substantially constant and the other varies with the speed of the booster pump; connections for causing the variable back pressure to actuate said timer and said controller; and connections for causing the constant back pressure to cause delivery of fuel to said fuel pump, and to said servomotor.

10. Fuel injection apparatus comprising in combination an injection pump having a fuel supply chamber and a subsidiary fuel chamber; a feeding pump aflixed to one face of the said injection pump for supplying liquid fuel under different pressures both to said fuel supply chamber and to said subsidiary fuel chamber; a regulating device ailixed to the opposite face of the injection pump; and displaceable means in said regulating device acted upon by the pressures of the liquid fuel in said supply and subsidiary chambers.

ERNST BCHAEREN. 

